Use Skia's matchFamilyStyleCharacter API for font fallback

third_party/WebKit/Source/platform/fonts/FontCache.cpp

Index: third_party/WebKit/Source/platform/fonts/FontCache.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/FontCache.cpp b/third_party/WebKit/Source/platform/fonts/FontCache.cpp
index acf8c409bb9d40e7af57e4f64e9a8c27e2c75966..a884adda1d956a0e8fac7f470147f0c774e6651b 100644
--- a/third_party/WebKit/Source/platform/fonts/FontCache.cpp
+++ b/third_party/WebKit/Source/platform/fonts/FontCache.cpp
@@ -415,5 +415,21 @@ void FontCache::dumpShapeResultCache(WebProcessMemoryDump* memoryDump)
     memoryDump->addSuballocation(dump->guid(), String(WTF::Partitions::kAllocatedObjectPoolName));
 }
 
+// SkFontMgr requires script-based locale names, like "zh-Hant" and "zh-Hans",
+// instead of "zh-CN" and "zh-TW".
+CString toSkFontMgrLocale(const String& locale)
+{
+    if (!locale.startsWith("zh", TextCaseInsensitive))
+        return locale.ascii();
+
+    switch (localeToScriptCodeForFontSelection(locale)) {
+    case USCRIPT_SIMPLIFIED_HAN:
+        return "zh-Hans";
+    case USCRIPT_TRADITIONAL_HAN:
+        return "zh-Hant";
+    default:
+        return locale.ascii();
+    }
+}
 
 } // namespace blink